Add missing since tag for SshBasicTestBase

Change-Id: Iad8ae9bb526418b279dc54a5e9d0c877c1eca475
diff --git a/org.eclipse.jgit.junit.ssh/src/org/eclipse/jgit/junit/ssh/SshBasicTestBase.java b/org.eclipse.jgit.junit.ssh/src/org/eclipse/jgit/junit/ssh/SshBasicTestBase.java
index f9ca0b8..da84b0e 100644
--- a/org.eclipse.jgit.junit.ssh/src/org/eclipse/jgit/junit/ssh/SshBasicTestBase.java
+++ b/org.eclipse.jgit.junit.ssh/src/org/eclipse/jgit/junit/ssh/SshBasicTestBase.java
@@ -22,6 +22,8 @@
  * Some minimal cloning and fetching tests. Concrete subclasses can implement
  * the abstract operations from {@link SshTestHarness} to run with different SSH
  * implementations.
+ *
+ * @since 5.11
  */
 public abstract class SshBasicTestBase extends SshTestHarness {